How Much is Your Kick Really Worth?
By Terry Laughlin
Most swimmers, down deep, probably suspect their legs don't help them out much in the speed department. But because the fastest swimmers in any group usually seem to be fastest when the kickboards are handed out, theyre reluctant to gamble on not doing kicking sets. Freestyle-world-record-holders Ian Thorpe, Alexandre Popov, Grant Hackett and Pieter VandenHoogenband can all kick a stunning sub-30-seconds for 50 meters, which leads many swimmers to the conclusion that a stronger kick is worth countless hours of kickboard sets.
While many of the fastest swimmers in the world are also very fast kickers, I'm reluctant to conclude that the logic behind it works this way:
1. They work very hard at their kickboard training so...
I'm more inclined to believe that the same talents that allow them to swim faster than virtually everyone else on earth also allow them to push a kickboard down a pool faster than virtually everyone else on earth. And Im somewhat skeptical that the kickboard sets led directly, or even indirectly, to the fast swims.
In fact, your kick does contribute something to propulsion, but not in the way most of us imagine. My sense is that most people vaguely think they need a good kick because either:
1. If my arms can propel my body at 4 feet per second and my legs can propel it at 2 feet per second, maybe together they can propel it at 6 feet per second, OR
2. If I really work hard at those kickboard-training sets, I'll get a more powerful "outboard motor," say a 40-horsepower Evinrude instead of the 20-hp model I have when I don't train diligently with a kickboard.
But it doesn't work that way. Yes, a swimmer kicking on a board creates propulsion, sometimes even fast propulsion. But that tells us nothing about how much a stronger kick adds to whole-stroke swimming, nor the energy cost of whatever good it might do.
Over 50 years ago coaching legend Doc Counsilman designed an experiment to actually measure what kicking adds to propulsion. He devised an apparatus to tow swimmers in a glide position at various speeds. Tension on the line was measured to see if it was greater, the same as, or less, when kicking than it was just gliding along.
The only instance in which kicking decreased tension on the line (i.e. added propulsion) was at slow towing speeds, with the swimmer kicking at maximum effort. But at any speed over 5 feet per second (1 minute per 100 yards) the kick contributed nothing and, in some instances, actually increased drag!
Counsilmans reaction?. Imagine, he suggested, a car with separate front- and rear-wheel drive. If the front wheels turn at 30 mph, but the rear wheels turn at 20 mph, the car's total speed will not be 50 but less than 30 mph, because the slower rear wheels create drag. The same thing happens, he contended, when a swimmer persists in emphasizing an inefficient kick. The kick consumes energy and adds drag. More work, less speed.
The energy cost of kicking has also been measured, in several studies that gauged the oxygen consumption of competitive swimmers while pulling only, kicking only, and swimming. Each found that hard kicking greatly increases the energy cost of moving at a given speed. In one instance, kicking at a speed of about 60 seconds for 50 yards--a rather moderate speed for any competitive swimmer--used four times as much oxygen as pulling at the same speed.
The obvious conclusion: Kicking can add only a modest amount of propulsion to an efficient stroke, while it can add a significant amount of drag and enormously increase the energy cost of whole-stroke swimming, if overemphasized. Therefore swimmers should do all they can to maximize the benefit of their kicking while minimizing the work they put into it.
Kick For Efficiency, Not for Speed
"Fine," you say. "If all kicking does is burn energy and cause drag, why bother to kick at all?" Well, because that's not all kicking does. An efficient kick will improve your stroke and, in fact, is essential for your body rotation to produce anything like the power it's capable of producing for you. Imagine a baseball pitcher trying to throw a fastball with his legs shackled. Or Venus Williams trying to hit a tennis serve without being allowed to step into it. Or a child, trying to swoop and soar on a playground swing while holding legs tucked tightly.
The key is to allow your legs to move in the most natural, efficient way. An efficient, impeccably timed kick can make body rotation far more potent, and cost very little energy. Skeptical? Stand with your feet a bit more than hip-width, arms hanging loosely. Keeping your feet flat, rotate right and left, letting your arms swing freely. You'll feel the fixed position of your legs impeding your movement, creating tension from your knees to your hips.
Now repeat, but allow your back heel to lift as you swing. You'll find that you rotate at least an additional 30 degrees in each direction, and eliminate the inhibiting tension.
Repeat the experiment one last time, but now add just a little push off the ball of your rear foot whenever it feels most natural to do so. When you time this gentle push correctly to body swing, you'll feel yourself rotate with even more speed and power.
Finally before you quit, try the same rotation/swing while fluttering your feet rapidly in place. See what happens? Right. Your coordination and efficiency break down and the movement degenerates into a shapeless mess. Uncoordinated leg movements always scuttle the rhythmic, driving momentum you can create when your legs and torso move with great coordination.
That demonstrates what happens when an efficient kick coordinates well good body rotation. It also shows what can happen with an inefficient kick--no matter how well conditioned it may have become through miles of diligent kickboard training. An inefficient kick adds drag and energy cost and contributes nothing to propulsion or speed. That final, uncoordinated twitching I suggested represents what happens to unbalanced swimmers. They feel their legs sinking, and move them more frantically. That not only fails to correct poor balance, it impedes fluid body rotation. A balanced swimmer's legs are free to coordinate smoothly with body movement.
The first example above--swinging with feet flat and fixed--is equivalent to a swimmer trying not to kick (or perhaps wearing a pull buoy). This will add tension or torque that impedes the free rotation of the body. The free-heel movement is the equivalent of a natural, non-overt, 2-beat kick, moving in coordination with body roll. This kind of kick feels effortless, almost unconscious, and is best for swimming longer distances or fitness or lap swimming. The third example, adding a well-timed push to your body swing, is the equivalent of putting a bit more snap into the downbeat of your 2-beat kick. If you add it at just the right time, you'll feel your hips drive with more power. And if you keep your armstroke connected to body roll, increased hip drive will translate into a more powerful stroke.
But it's critical that you first establish impeccable timing in your 2-beat kick, and that you can sense where to add the extra snap just as easily as you can while standing in the middle of the room and swinging back and forth.
And finally, the main issue isnt simply whether kickboard training is a waste of time, but whether there might be some better use of the precious time spent splashing noisily back and forth on a kickboard. In the next issue, Ill describe how to develop efficient kicking action in each stroke and some alternatives to kickboard training.
This article was excerpted from Swimming Made Easy published in January 2001 by Total Immersion Inc. Read another free sample chapter at www.totalimmersion.net/products/140chapter.html or click here for order info.
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